CETAC M-7600 Mercury Analyzer Operator's Manual

Operator’s Manual
Chapter 5: Maintaining the Mercury Analyzer
Replacing the Hg Lamp Bulb
The effect of lamp current on data quality (absorbance and noise) is minimal
over the range 2 – 15 mA. When a lamp is new, the normal operating lamp
current is 2 – 5 mA. As the lamp ages, the lamp current will automatically
adjust to maintain constant emission intensity reaching the EOFM
filter/detector.
WARNING
ULTRAVIOLET RADIATION HAZARD
Before opening the cover, turn off the power switch and disconnect the
power cord. Sustained exposure of eyes to UV rays emitted from the lamp
may result in permanent eye injury.
When to Replace or Service the Lamp
If the OVER RANGE indicator on the front of the mercury analyzer remains
illuminated for more than 15 minutes when the mercury analyzer is turned on,
it is time to consider replacing the lamp. The OVER RANGE indicator is
illuminated whenever the current through the lamp exceeds a certain
threshold.
Cleaning the EOFM
The electro-optical feedback monitor (EOFM) monitors the output of the lamp
and adjusts the lamp current to ensure constant light intensity as the lamp
ages. A filter ensures that the lamp output is measured only at the correct
wavelength.
Use a dentist mirror and flashlight to check that the EOFM filter is not
“smudged.” Refer to Figure 5-18. If it's clean, order a replacement lamp.
If the EOFM filter is dirty, clean in place using the cell cleaning procedure. If the
OVER RANGE indicator continues to stay on, or if you need greater absorbance
sensitivity than the old “high current” lamp can provide, replace the lamp.
Lamp
Assembly
Cells
Detector
Assembly
Figure 5-18
M-7600 Optical Rail.
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